1. Field of the Invention
The present invention generally relates to microfabrication techniques and, in particular, to a microfabricated electromagnetic system and a method for forming electromagnets integrated within microfabricated devices.
2. Related Art
As known in the art, microfabrication processes are utilized to construct small, low profile devices that can be batch fabricated at a relatively low cost. In this regard, multiple devices are typically manufactured on a single wafer during microfabrication. Well known microfabrication techniques are used to form similar components of the multiple devices during the same manufacturing steps, and once the multiple devices have been formed, they can be separated into individual devices. Examples of microfabrication techniques that allow the batch fabrication of multiple devices are, but are not limited to, techniques commonly used in integrated circuit fabrication (e.g., diffusion, implantation, oxidation, chemical vapor deposition, sputtering, evaporation, wet and dry etching, etc.), electroforming (e.g., electroplating, electrowinning, electrodeposition, etc.), packaging techniques (e.g., lamination, screen printing, etc.), photolithography, and thick or thin film fabrication techniques. Since a large number of devices can be formed by the same microfabrication steps, the costs of producing a large number of devices through microfabrication techniques are less than the costs of serially producing the devices through other conventional techniques. Accordingly, it is desirable, in most applications, to fabricate devices through microfabrication techniques.
In many applications, it is also desirable for the devices to include an electromagnet in order to actuate certain features of the device or to perform other functionality. Furthermore, as known in the art, the strength of an electromagnetic flux may be increased by increasing the number of turns of the electromagnet's coil. Therefore, many conventional designs for electromagnets wind the coils around magnetic material through multiple turns in order to generate a sufficient electromagnetic flux for a particular application.
As known in the art, winding the coils concentrically around the magnetic material in the same plane can cause leakage losses. This is because the amount of flux concentrated in the magnetic material of the electromagnet is decreased as the electromagnet's coil is positioned further from the magnetic material of the electromagnet. In order to keep the electromagnet's coils close to the magnetic material for minimizing leakage losses, most conventional designs for electromagnets spiral the coil around the magnetic material in a non-planar fashion until the number of desired turns is reached.
However, conventional non-planar windings are difficult to achieve through conventional microfabrication techniques. As a result, most conventional devices have coils that are not batch fabricated through microfabrication techniques. Instead, the coils for each electromagnet are usually formed individually by mechanically wrapping the coils around magnetic material or by other techniques that individually form the coils of each electromagnet. Accordingly, the costs of manufacturing the electromagnets are increased since the benefits of batch fabrication are not utilized in forming the coils of the electromagnets.
Another problem increasing the difficulty of microfabricating efficient electromagnets is flux saturation. As known in the art, magnetic material has a flux density that limits the amount of flux that a given cross-sectional area of magnetic material can carry. Therefore, when the area of magnetic material for a conventional electromagnet is reduced to a microfabricated scale, the amount of flux capable of being carried by the magnetic material is also reduced. As a result, many conventional designs for electromagnets are inadequate for producing a sufficient electromagnetic flux at a microfabricated scale.
Thus, a heretofore unaddressed need exists in the industry for providing a system and method of efficiently microfabricating an electromagnet and for reducing the effects associated with flux saturation, and leakage.